Donald Trump is not fit to be president of the United States. Many people have said it — politicians of both parties, economists, pundits, business leaders — but millions of GOP primary voters don't seem to be listening. Much of the Republican base has taken leave of its senses, a flight blamed alternately on inchoate anger, disgust with inside-the-Beltway candidates and misplaced affection for a plain-speaking cartoon character who often seems to utter whatever nonsense comes into his head. Regardless of the reason for his popularity, the bombastic billionaire continued his soon-to-be unstoppable march toward the nomination Tuesday, racking up resounding victories in primaries across the American South and in the Northeast.

The reality is that Trump has no experience whatsoever in government, interacting with the machinery of state only as a supplicant. He has shamefully little knowledge of the issues facing the country and the world, and a temperament utterly unsuited to the job. He is a racist and a bully, a demagogue. He has proposed killing the families of terrorists, a violation of international law so blatant that a former CIA director predicted that U.S. troops would refuse to carry out such an order.

He mocked a disabled person at a campaign rally. He has vowed to reinstate waterboarding and forms of torture that are “much worse.” He intends to seize and deport 11 million people living in the U.S. illegally. He would bar all Muslims from entering the country until further notice. He would “open up our libel laws” so that news organizations are punished for writing critical “hit” pieces. He wants to build a wall along the entire Mexican border, on the fantastical premise that he could force the Mexican government to pay for it. He has threatened to start trade wars with two of the country’s biggest trading partners, Mexico and China, by slapping on the kind of protectionist tariffs that U.S. leaders have been trying for decades to eliminate worldwide.

Often enough he says nothing at all, promising to replace Obamacare, for instance, with “something great” or assuring listeners vaguely that a winner such as himself — someone who never tires of telling the world he’s rich, successful and famous — will make it all work out one way or another.

It isn't easy to tell how much of Trump's performance is merely shtick and how much is real. In the aftermath of his victories Tuesday, Trump struck a less adversarial tone and talked about how he was “becoming diplomatic.” Yet at the same time, he said this of House Speaker Paul D. Ryan (R-Wis.), one of several GOP leaders who suggested Trump hadn’t disavowed an endorsement by former KKK leader David Duke forcefully enough: “Paul Ryan, I don’t know him well, but I’m sure I’m going to get along great with him. And if I don’t, he’s going to have to pay a big price, OK?” That’s about as diplomatic a message as a dead fish wrapped in newspaper.

We hope we won't have to learn who the real Donald J. Trump might be. Not that we find much to like about his Republican opponents, with whom we disagree sharply on issues that include climate change, environmental protection, healthcare and reproductive rights. In fact, on issues where it’s possible to discern where Trump stands, his views are more moderate at times than those of his principal GOP rivals. And in their zeal to slow Trump’s momentum, some have begun sinking to the Donald’s level as a campaigner, slinging personal insults (at times vulgar ones) instead of focusing on the problems with his record and his campaign. Nevertheless, those candidates are more rational, knowledgeable, understandable and predictable — all of which are necessary (albeit not sufficient) qualities in the Oval Office. Trump’s blustery temperament and authoritarian notion of the presidency are unique in the field and uniquely disqualifying.

Trump’s popularity may simply be the product of a toxic brew of a polarized two-party system and nihilistic tactics on the campaign trail and Capitol Hill (such as shutting down the government and threatening to default on U.S. debts) that, either by design or in effect, have convinced many Americans that their government is irreparably broken and corrupt. But Trump isn’t the answer — he’s just a cynical manipulator playing on the very real frustrations of voters tired of a government that takes big, difficult problems and makes them intractable. Those voters still have time to choose a better standard-bearer.